docs: def lt(self, other):
          """
          Strictly less than. Returns True if no part of this Interval
          extends higher than or into other.
          :raises ValueError: if either self or other is a null Interval
          :param other: Interval or point
          :return: True or False
          :rtype: bool
          """
          self._raise_if_null(other)
          return self.end <= getattr(other, 'begin', other)